Transducer Module

ABSTRACT

Transducer modules for use in a blood analysis instrument and methods for analyzing a blood sample. The transducer modules presented generally include a light source, a focus-alignment system, a flow cell, and a light scatter detection system. Electrodes within the flow cell allow for the measurement of the DC impedance and RF conductivity of cells passing through a cell-interrogation zone in the flow cell. Light scatter from the cells passing through the cell-interrogation zone is measured by the light scatter detection system. The light scatter detection system measures the light scatter parameters of upper median light scatter, lower median angle light scatter, low angle light scatter, and axial light loss. The presented methods for analyzing a blood sample generally include aspirating a whole blood sample into a blood analysis instrument, preparing the blood sample for analysis, passing the blood sample through a flow cell in a transducer system, and measuring axial light loss, multiple angles of light scatter, DC impedance and/or RF conductivity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional that claims priority pursuant to 35U.S.C. §120 to U.S. application Ser. No. 12/178,817, filed on Jul. 24,2008, the entire disclosure of which is hereby incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems and methods for analyzing awhole blood sample. More specifically, the present invention relates toa transducer module for use in a blood analysis instrument.

2. Background Art

In diagnosing different illnesses and disease states, it is common toanalyze a patient's peripheral blood to differentiate and enumerate thevarious constituents within the blood, as well as to determine certainparameters or characteristics of those constituents. For example, awhole blood sample (WBS) generally comprises various types of cells(both blood cells and non-blood cells) suspended in a liquid medium orplasma. The blood cells are three basic types, namely, red cells(erythrocytes), white cells (leukocytes), and platelets (thrombocytes).Depending on the level of maturity, red cells are often furtherclassified into three subsets, namely, nucleated red blood cells(NRBCs), reticulated red cells (“retics”), and mature red blood cells(RBCS). Mature white cells fall into one of five different subsets,namely, monocytes, lymphocytes, eosinophils, neutrophils and basophils.Each of the white cell subsets can be further classified into subclassesbased on their respective level of maturity, activation or abnormality.Platelets are of three general types, namely, mature platelets,reticulated platelets and large platelets. A thorough blood analysisdetermines the respective concentrations and relative percents of eachof the above cell types and subsets.

Various measurement techniques, alone or in combination, have beenimplemented in blood analysis instruments to differentiate and enumeratethe various constituents in a WBS. For example, direct current (DC)impedance measurements are used to measure the volume of a cell. DCimpedance measurements accurately size a cell within an isotonic diluentregardless of the cell type, orientation, maturity, and/or othercharacteristics. Radio frequency (RF) measurements are used to measurethe conductivity of a cell to collect information about cell size andinternal structure, including chemical composition and nuclear volume.Further, when a cell is irradiated by a light source, such as a laserbeam, the cell scatters light in all directions. Measurements of lightscatter at various distinct angles are used to obtain information suchas cellular granularity, nuclear lobularity, and cell surface structure.Fluorescence measurements of a stained blood sample have been used fordifferentiating blood sample constituents. The respective outputs ofthese measurement techniques are then processed to identify andenumerate the constituents and thereby develop a comprehensive bloodanalysis report.

U.S. Pat. No. 6,228,652 (“the '652 patent”), which is herebyincorporated by reference in its entirety, discloses, inter alia, ablood analysis instrument. The blood analysis instrument of the '652patent includes a single transducer for simultaneously measuring the DCimpedance, RF conductivity, light scattering, and fluorescencecharacteristics of blood cells passing one-at-a-time through acell-interrogation zone in a flow cell. A laser is used for irradiatingthe cells passing through the cell-interrogation zone. The light scatterfrom the individual cells is then measured. Simultaneously, thefluorescence of each cell is measured to identify NRBC populations.However, the use of fluorescence to identify NRBCs is relativelyexpensive due to the high costs of the system components and fluorescentdyes needed to stain the blood sample. Further, in practice, therelatively tight tolerances needed for optical focusing and alignment ofthe laser within the cell-interrogation zone presents a significantmanufacturing challenge.

U.S. Pat. No. 7,208,319 (“the '319 patent”), which is herebyincorporated by reference in its entirety, discloses, inter alia,alternative methods for differentiating NRBCs. The methods of the '319patent include passing a prepared blood sample through a flow cell,irradiating the individual cells of the sample as they pass through thecell-interrogation zone of the flow cell, and measuring combinations ofDC impedance, axial light loss, low angle light scatter, and medianangle light scatter.

Additional systems and methods are described in U.S. Pat. Nos.5,125,737; 5,616,501; 5,874,311; 6,232,125; 7,008,792; and 7,208,319,the disclosures of which are hereby incorporated by reference in theirentireties.

BRIEF SUMMARY OF THE INVENTION

Provided herein are transducer modules for use in a blood analysisinstrument and methods for analyzing a blood sample. The transducermodules presented generally include a light source, a focus-alignmentsystem, a flow cell, and a light scatter detection system. Electrodeswithin the flow cell allow for the measurement of the DC impedance andRF conductivity of cells passing through a cell-interrogation zone inthe flow cell. Light scatter from the cells passing through thecell-interrogation zone is measured by the light scatter detectionsystem. The light scatter detection system measures the light scatterparameters of upper median light scatter, lower median angle lightscatter, low angle light scatter, and axial light loss. The presentedmethods for analyzing a blood sample generally include aspirating awhole blood sample into a blood analysis instrument, preparing the bloodsample for analysis, passing the blood sample through a flow cell in atransducer system, and measuring axial light loss, multiple angles oflight scatter, DC impedance and/or RF conductivity.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated herein, form part ofthe specification and illustrate embodiments of a transducer module andmethods for analyzing a blood sample. Together with the description, thedrawings further serve to explain the principles of and to enable aperson skilled in the relevant art(s) to make and use the transducermodules and methods described herein. In the drawings, like referencenumbers indicate identical or functionally similar elements.

FIG. 1 is a system block diagram of a blood analysis instrumentincorporating a transducer module in accordance with one embodimentpresented herein.

FIG. 2 is a block diagram of the transducer module of FIG. 1.

FIG. 3 is a perspective view of a transducer module in accordance withone embodiment presented herein.

FIG. 4 is a side view of the transducer module of FIG. 3.

FIG. 5 is a sectional view of the transducer module of FIG. 3.

FIG. 6 is an alternative sectional view of the transducer module of FIG.3.

FIG. 7 is a sectional view of a light scatter detector unit inaccordance with one embodiment presented herein.

FIG. 8 is a sectional view of a light scatter detector unit inaccordance with another embodiment presented herein.

FIG. 9 is a sectional view of a light scatter detector unit inaccordance with another embodiment presented herein.

FIG. 10 is a sectional view of a lens mounted on a flexure hinge inaccordance with one embodiment presented herein.

FIG. 11 is a sectional view of a lens mounted on a flexure hinge inaccordance with one embodiment presented herein.

FIG. 12 is a flowchart illustrating a method of analyzing a bloodsample.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description of transducer modules and methods foranalyzing a whole blood sample (WBS) refers to the accompanying drawingsthat illustrate exemplary embodiments. Other embodiments are possible.Modifications may be made to the embodiments described herein withoutdeparting from the spirit and scope of the present invention. Therefore,the following detailed description is not meant to be limiting. Further,it would be apparent to one of skill in the art that the systems andmethods described below may be implemented in many different embodimentsof hardware, software, and/or firmware. Any actual hardware, software,and/or firmware described is not meant to be limiting. The operation andbehavior of the systems and methods presented are described with theunderstanding that modifications and variations of the embodiments arepossible given the level of detail presented.

Before describing the presented transducer modules and methods foranalyzing a WBS in detail, it is helpful to describe an exampleenvironment in which the transducer modules and methods may beimplemented. As discussed above, various blood analysis instruments havebeen developed to differentiate and enumerate various constituents in aWBS. As such, the transducer modules and methods presented herein areparticularly useful in the environment of a blood analysis instrument.While the description provided incorporates the transducer modules andmethods into a blood analysis instrument, the transducer modules andmethods should not be limited to the environment of a blood analysisinstrument. One of skill in the art would readily understand how toincorporate the presented transducer modules and methods in alternativeenvironments, such as, for example, flow cytometry systems, cell sortingsystems, DNA analysis systems, etc.

FIG. 1 is a system block diagram a transducer module 100 incorporated ina blood analysis instrument 105. Within instrument 105 are three coresystem blocks, namely, a preparation system 120, a transducer system ormodule 100, and an analysis system 140. While instrument 105 is hereindescribed at a very high level, with reference only to the three coresystem blocks (120, 100, and 140), one of skill in the art would readilyunderstand that instrument 105 includes many other system componentssuch as central control processor(s), display system(s), fluidicsystem(s), temperature control system(s), user-safety control system(s),etc.

In operation, a whole blood sample (WBS) 110, is presented to instrument105 for analysis. WBS 110 is preferably aspirated into instrument 105.Aspiration techniques are known to those skilled in the relevant art.After aspiration, WBS 110 is delivered to preparation system 120.Preparation system 120 receives WBS 110 and performs the operationsnecessary to prepare WBS 110 for further measurement and analysis. Forexample, preparation system 120 may separate WBS 110 into predefinedaliquots for presentation to transducer module 100. Preparation system120 may also include mixing chambers so that appropriate reagents may beadded to the aliquots. For example, if an aliquot is to be tested fordifferentiation of white blood cell subset populations, a lysing reagentmay be added to the aliquot to break up and remove the RBCs. Preparationsystem 120 may also include temperature control components to controlthe temperature of the reagents and/or mixing chambers. Appropriatetemperature controls improve the consistency of the operations ofpreparation system 120.

From preparation system 120, the predefined aliquots are transferred totransducer module 100. As described in further detail below, transducermodule 100 performs the intended measurements. The measured parametersare then delivered to analysis system 140 for data processing. Analysissystem 140 includes computer processing algorithms to evaluate themeasured parameters, identify and enumerate the WBS constituents, andthereafter produce a comprehensive blood analysis report 150. Finally,excess sample from transducer module 100 is directed to an external (oralternatively internal) waste system 160.

FIG. 2 is a system block diagram illustrating components of transducermodule 100. Transducer module 100 includes a light source, such as alaser 210. In one embodiment, laser 210 is a 635 nm, 5 mW, solid-statelaser. Laser 210 emits a beam 215.

In the embodiment shown, a focus-alignment system 220 adjusts beam 215such that a resulting beam 225 is focused and positioned at acell-interrogation zone 233 of a flow cell 230. Flow cell 230 receives asample aliquot from preparation system 120. In one embodiment,additional fluidics (not shown) are employed to allow for hydrodynamicfocusing of the sample aliquot within flow cell 230. The aliquotgenerally flows through the cell-interrogation zone 233 such that itsconstituents pass through the cell-interrogation zone 233 one at a time.In one embodiment, a cell-interrogation zone, such as the one describedin the '652 patent, is employed. For example, cell-interrogation zone233 may be defined by a square transverse cross-section measuringapproximately 50.times.50 microns, and having a length (measured in thedirection of flow) of approximately 65 microns.

As would be appreciated by one of skill in the art, flow cell 230includes two electrodes 231, 232 for performing DC impedance and RFconductivity measurements of the cells passing throughcell-interrogation zone 233. The signals from electrodes 231, 232 arethen transmitted to analysis system 140.

Beam 225 irradiates the cells passing through cell-interrogation zone233, resulting in light scatter 240. In the embodiment shown in FIG. 2,light scatter 240 is detected by a light scatter detector assembly 250.Light scatter detector assembly 250 differs from previously availableassemblies in that it comprises a first light scatter detector unit 250Aand a second light scatter detector unit 250B posterior to the first. Asbest illustrated in FIG. 7, first light scatter detector unit 250Aincludes a first photoactive region 715 for detecting and measuringupper median angle light scatter (UMALS). First light scatter detectorunit 250A also includes a second photoactive region 710 for detectingand measuring lower median angle light scatter (LMALS).

In one embodiment, first light scatter detector unit 250A furtherincludes one or more masks to block light scatter in selective portionsof the photoactive regions and thereby improve the detector'ssignal-to-noise ratio. For example, in the embodiment shown in FIG. 7,mask 720 is provided. Further, in the embodiment shown in FIG. 7, anopening 251 is provided to allow low angle light scatter to pass beyondfirst light scatter detector unit 250A and thereby reach and be detectedby second light scatter detector unit 250B. Wires 750 transmit thesignal from light scatter detector unit 250A to analysis system 140 forfurther processing.

In an alternative embodiment, as shown in FIG. 8, first light scatterdetector unit 250A may be designed as a split sensor. As shown in FIG.8, first light scatter detector unit 250A includes a first photoactiveregion 815 for detecting and measuring upper median angle light scatter(UMALS), and a second photoactive region 810 for detecting and measuringlower median angle light scatter (LMALS). Opening 251 is provided toallow low angle light scatter to pass beyond first light scatterdetector unit 250A and thereby reach and be detected by second lightscatter detector unit 250B. While opening 251 is shown as a circularopening in FIGS. 7 and 8, opening 251 is not limited in size or shape,and may be designed in to any appropriate size or shape. Wires 850transmit the signal from light scatter detector unit 250A to analysissystem 140 for further processing.

In one embodiment, a second light scatter detector unit 250B includesone or more low angle light scatter (LALS) sensors. In the embodimentillustrated in FIG. 9, second light scatter detector unit 250B includesfour LALS sensors 970 disposed radially around an axial light loss (ALL)sensor 960. LALS sensors 970 and ALL sensor 960 are mounted on a baseboard 910, such as a printed circuit board (PCB), and covered by a mask325. In the embodiment shown, a plurality of bolts 930 (only one boltshown) are used to secure mask 325 to board 910. A plurality of openings920 in mask 325, including a central opening 921, allows for a moreprecise control of the light scatter angles that reach the sensors 960,970. Use of mask 325 allows a manufacturer to limit the light scatterangles beyond the manufacturing limits of the LALS sensors and ALLsensor. For example, a manufacturer can use over-sized LALS sensors andthen employ mask 325 to define the precise light scatter angles to bemeasured. If the LALS and ALL sensors are manufactured to theappropriate tolerances, then there would be no need for mask 325.

In one embodiment, first photoactive region 815 is used to detect andmeasure UMALS, which is defined as light scatter at angles between about20 and about 43 degrees. In alternative embodiments, first light scatterdetector unit 250A can be sized and/or positioned such that firstphotoactive region 815 is used to detect and measure light scatter atangles greater than about 43 degrees. Second photoactive region 810 isused to detect and measure LMALS, which is defined as light scatter atangles between about 9 and about 19 degrees. In alternative embodiments,first light scatter detector unit 250A can be sized and/or positionedsuch that second photoactive region 815 is used to detect and measurelight scatter at angles less than about 9 degrees. A combination ofUMALS and LMALS is defined as median angle light scatter (MALS), whichis light scatter at angles between about 9 degrees and about 43 degrees.LALS sensors 970 are used to detect and measure LALS, which is definedas light scatter at angles less than about 10 degrees, including 1.9degrees .+−.0.5 degrees, 3.0 degrees .+−.0.5 degrees, 3.7 degrees.+−.0.5 degrees, 5.1 degrees .+−.0.5 degrees, 6.0 degrees .+−.0.5degrees, and 7.0 degrees .+−.0.5 degrees. ALL sensor 960 is used todetect and measure light loss at angles less than about one degree, andin one embodiment angles less than about 0.5 degrees. As such, theassembly presented, and equivalent structures, differ from previouslyavailable assemblies in that they provide means for detecting andmeasuring ALL and multiple distinct light scatter angles. For example,light scatter detector assembly 250, including appropriate circuitryand/or processing units, provide a means for detecting and measuringUMALS, LMALS, LALS, MALS and ALL.

FIG. 3 is a perspective view of a transducer module 100 in accordancewith one embodiment presented herein. FIG. 4 is a side view of thetransducer module of FIG. 3. FIG. 5 is a blown-up sectional view oftransducer module 100 showing first light scatter detector unit 250Aappropriately mounted within flow cell 230. FIG. 6 is an alternativesectional view of transducer module 100. For illustrative purposes, FIG.6 depicts first light scatter detector unit 250A partially withdrawnfrom flow cell 230.

In the embodiment depicted in FIGS. 3-6, transducer module 100 generallyincludes a relatively fixed laser 210, focus-alignment system 220, arelatively fixed flow cell 230, and light scatter detector assembly 250.These components are mounted on a base board 305, and thereafterincorporated into a blood analysis instrument. One of skill in the artwould readily understand that in alternative embodiments one or morecomponents of transducer module 100 may be removed or repositioned. Oneof skill in the art would also readily understand that in alternativeembodiment one or more components of transducer module 100 may bereplaced with equivalent components to perform similar functions.

In the embodiment shown, laser 210 is mounted on block 307 in arelatively fixed position. As used herein, the term “fixed” or“relatively fixed” is not intended to mean permanently set, but insteadis intended to mean “anchored such that an end-user does not need tomake positional adjustments.” The relatively fixed position of laser 210contrasts with previously available systems where an end-user would haveto conduct tedious and time-consuming adjustments of both the laser andflow cell in order to properly focus and position the laser beam in thecell-interrogation zone of the flow cell. In the system depicted inFIGS. 3 and 4, the beam emitted by laser 210 is focused and positionedby focus-alignment system 220. Focus-alignment system 220 includes afirst lens 411 mounted on a first adjustment means 413 (as best shown inFIG. 10) and a second lens 311 mounted on a second adjustment means 313(as best shown in FIG. 11), wherein the second adjustment means ismounted on a movable carrier 315.

In the embodiment shown, first adjustment means 413 is a flexure hinge,mounted on block 309. As depicted, first adjustment means 413 includes aset screw 1010 and an adjustment spring 1020 for positional adjustmentof first lens 411. The positional adjustment of first lens 411 therebyprovides lateral movement, and thus lateral alignment, of the laser beampassing through first lens 411. Flexure hinges are well known, asdescribed in U.S. Pat. No. 4,559,717, which is hereby incorporated byreference in its entirety. As would be evident to one of skill in theart, any equivalent structure may be employed with the end objective ofproviding lateral alignment of the laser beam passing through first lens411. As such, first adjustment means 413, and equivalents thereof,provides means for lateral alignment of the laser beam in thex-direction relative to laser 210.

In the embodiment shown, second adjustment means 313 is a flexure hingemounted on movable carrier 315. Second adjustment means 313 includes aset screw 1110 and an adjustment spring 1120 for positional adjustmentof second lens 311. The positional adjustment of second lens 311 therebyprovides longitudinal (or vertical) movement, and thus longitudinalalignment, of the laser beam passing through second lens 311. As wouldbe evident to one of skill in the art, any equivalent structure may beemployed with the end objective of providing longitudinal alignment ofthe laser beam passing through second lens 311. As such, secondadjustment means 313, and equivalents thereof, provides means forlongitudinal alignment of the laser beam in the y-direction relative tolaser 210.

One of skill in the art would understand that although the abovedescribed embodiment presents first adjustment means 413 as providinglateral alignment and second adjustment means 313 providing longitudinalalignment, a system wherein first adjustment means 413 provideslongitudinal alignment and second adjustment means 313 provides lateralalignment, would be an equivalent system.

Movable carrier 315 is provided to axially position the focal point ofthe laser beam passing through second lens 311. Movable carrier 315includes a wedge assembly 317, a biasing spring 450, and a set screw 319to move movable carrier 315 forward or backward, along the z-directionrelative to laser 210. Forward and backward movement of movable carrier315 places the focal point of the laser beam in cell-interrogation zone233 of flow 230. As such, movable carrier 315, and equivalents thereof,provides means for axial positioning of the focal point of the laserbeam in the z-direction relative to laser 210.

The positional movement and/or adjustment of first adjustment means 413,second adjustment means 313, and movable carrier 315 allows for theprecise positioning of the focal point of the laser beam within thecell-interrogation zone 233. As such, a manufacturer may fix flow cell230 to a system block 321 relative to laser 210, within manufacturabletolerances, and thereafter provide for fine adjustments of the positionof the focal point of the laser beam to properly irradiatecell-interrogation zone 233 of flow cell 230.

Upon irradiation by the laser beam, light scatter is detected by a lightscatter detector assembly, such as the exemplary light scatter detectorassembly 250 described above. For example, light scatter detectorassembly 250 is depicted as comprising first light scatter detector unit250A mounted within flow cell 230 and second light scatter detector unit250B mounted on system block 323.

FIG. 12 is a flowchart illustrating a method 1200 of analyzing a bloodsample using, for example, transducer module 100. One of skill in theart would appreciate that the method presented in FIG. 12 is not limitedto use solely with the transducer module 100 described herein, butinstead can be performed using alternative systems.

In step 1210, a WBS is aspirated into a blood analysis instrument. Instep 1220, the blood sample is prepared by dividing the sample intoaliquots and mixing the aliquot samples with appropriate reagents. Instep 1230, the aliquot samples are passed through a flow cell in atransducer system such that constituents of the aliquot samples passthrough a cell-interrogation zone in a one-by-one fashion. Theconstituents are irradiated by a light source, such as a laser. In step1240, any combination of RF conductivity 1241, DC impedance 1242, LALS1243, ALL 1244, UMALS 1245, and/or LMALS 1246 are measured. Themeasurements of UMALS 1245 and LMALS 1246 may then be used to determineMALS 1247. Alternatively, MALS 1247 may be measured directly. Theresulting measurements are then processed, in step 1250, to ultimatelyproduce a blood analysis report. Method 1200 differs from previouslyknown methods in that the system described above allows for thesimultaneous measurement of ALL with multiple distinct light scatterangles. For example, method 1200 simultaneously measures UMALS, LMALS,MALS, LALS, and ALL.

EXAMPLES

The following paragraphs serve as examples of the above-describedsystems. The examples provided are prophetic examples, unless explicitlystated otherwise.

Example 1

In one embodiment, there is provided a light scatter detector assemblycomprising a first light scatter detector unit and a second lightscatter detector unit. The first light scatter detector unit includes afirst photoactive region for detecting UMALS, a second photoactiveregion for detecting LMALS, and an opening provided to allow low anglelight scatter to pass beyond the first light scatter detector unit. Thesecond light scatter detector unit is posterior to the first lightscatter detector unit, and includes an axial light loss sensor. Thesecond light scatter detector unit further includes one or more LALSsensors disposed proximate to the axial light loss sensor.

Example 2

In one embodiment, there is provided a laser light focus-alignmentsystem for use in a transducer module, comprising a first adjustmentmeans for lateral alignment of a laser beam and a second adjustmentmeans for longitudinal alignment of the laser beam. The secondadjustment means is mounted on a movable carrier such that movement ofthe carrier axially positions a focal point of the laser beam. In oneembodiment, the first adjustment means includes a first lens, whereinpositional movement of the first lens aligns the laser beam in ax-direction, the second adjustment means includes a second lens, whereinpositional movement of the second lens aligns the laser beam in ay-direction, and the movement of the movable carrier positions the focalpoint of the laser beam in a z-direction, wherein the x-direction,y-direction, and z-direction are relative to a laser light source. Inalternative embodiments, the first adjustment means includes a flexurehinge and the second adjustment means includes a flexure hinge.

Example 3

In one embodiment, there is provide a transducer module comprising afixed laser light source, a first lens proximate to the laser lightsource for lateral alignment of a laser beam emitted by the laser lightsource, a second lens mounted on a movable carrier, wherein the secondlens provides longitudinal alignment of the laser beam, and whereinmovement of the carrier axially positions a focal point of the laserbeam, and a fixed flow cell.

Example 4

In one embodiment, there is provided a transducer module comprising afixed laser light source, a first lens proximate to the laser lightsource for lateral adjustment of a laser beam emitted by the laser lightsource, a second lens mounted on a movable carrier, wherein the secondlens longitudinally adjusts the laser beam, and wherein movement of thecarrier axially positions a focal point of the laser beam, a fixed flowcell, and a light scatter detector assembly. The light scatter detectorassembly includes a first light scatter detector unit having a firstphotoactive region for detecting UMALS, a second photoactive region fordetecting LMALS, and an opening provided to allow low angle lightscatter to pass beyond the first light scatter detector unit. The lightscatter detector assembly also includes a second light scatter detectorunit posterior to the first light scatter detector unit. The secondlight scatter detector unit includes an ALL sensor. In one embodiment,the transducer module further comprises one or more LALS sensorsdisposed proximate to the axial light loss sensor.

Example 5

In one embodiment, there is provided a method comprising aspirating ablood sample, preparing the blood sample for analysis, and passing theblood sample through a flow cell in a transducer system such that thetransducer system irradiates the blood sample. The method furtherincludes detecting and measuring light scatter parameters of ALL, LALS,UMALS, and LMALS. The method may further comprise detecting andmeasuring DC impedance, RF conductivity, and MALS. Alternatively, themethod may comprise calculating MALS from the measured UMALS and LMALS.

Example 6

In one embodiment, there is provided a method comprising aspirating ablood sample, preparing the blood sample for analysis, and passing theblood sample through a flow cell in a transducer system such that thetransducer system irradiates the blood sample, and detecting andmeasuring ALL and four distinct angles of light scatter.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed.Other modifications and variations may be possible in light of the aboveteachings. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical applicationand to thereby enable others skilled in the art to best utilize theinvention in various embodiments and various modifications as are suitedto the particular use contemplated. It is intended that the appendedclaims be construed to include other alternative embodiments of theinvention.

1. A light scatter detector assembly, comprising: a first light scatterdetector unit having a first photoactive region for detecting uppermedian angle light scatter, a second photoactive region for detectinglower median angle light scatter, and an opening provided to allow lowangle light scatter to pass beyond the first light scatter detectorunit; and a second light scatter detector unit posterior to the firstlight scatter detector unit, wherein the second light scatter detectorunit includes an axial light loss sensor.
 2. The light scatter detectorassembly of claim 1, further comprising: one low angle light scattersensor disposed proximate to the axial light loss sensor.
 3. The lightscatter detector assembly of claim 1, further comprising: a plurality oflow angle light scatter sensors disposed proximate to the axial lightloss sensor.
 4. The light scatter detector assembly of claim 3, whereinthe plurality of low angle light scatter sensors are positioned todetect light scatter of about five degrees.
 5. The light scatterdetector assembly of claim 1, wherein the first light scatter detectorunit includes a mask.
 6. The light scatter detector assembly of claim 1,wherein the second light scatter detector unit includes a mask.
 7. Thelight scatter detector assembly of claim 1, wherein the firstphotoactive region detects light scatter at angles greater than about 43degrees.
 8. The light scatter detector assembly of claim 1, wherein thesecond photoactive region detects light scatter at angles less thanabout 9 degrees.